Pressure vessels are used in chemical processes and often operate by introducing a flow of fluid through the top of the vessel, and acting on that flow as it passes downward through media within the vessel. The fluid is typically discharged through an outlet disposed at or near the bottom of the vessel. The inlet of the pressure vessel is in many cases simply a pipe or tube stub attached to inlet piping connected to the vessel.
As will be appreciated, distribution of the inlet flow can have a great effect on the efficiency of the media in the vessel. Several methods have been employed to enhance inlet flow distribution, with varying degrees of success. In some cases, the inlet region can be provided with a deflector plate that prevents flow from simply impinging at full velocity directly downward into the media. In other cases a basic screen has been used, with little or no flow control. The screen can also be used to prevent media from migrating into the inlet pipe during backflow phases of operation, but otherwise it does little to improve flow performance. Other techniques include the introduction of header lateral assemblies within the pressure vessel. Such arrangements can include a set of branching pipes that connect to the inlet, extending into the vessel in a “ladder” or “star-shaped” pattern. Such headers/laterals are undesirable because they require additional support in the vessel and have a high implementation cost. In some cases a full vessel diameter screen, a tube sheet (plate with a pattern of screen or pip nozzles) or a perforated plate are used, again with varying results.